Toggl - Toggl is an online time tracking tool. It features 1-click time tracking and helps you see where your time goes. Free and paid versions are available.
TimeLeft - TimeLeft is a versatile desktop utility - it can be used as a countdown clock, reminder, clock...
RescueTime - Time management software that shows you how you spend your time & provides tools to help you be more productive.
Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
Clockify - Simple and free time tracker. Perfect for small and mid-sized businesses as well as freelancers. Unlimited projects and users, unlimited productivity. Get all the premium functionalities, completely free.
wnr - Better than pomodoro, this timer app balances work and rest.